I have been told that if I have the license for mobile twinning, and a PRI T1 that (depending on the carrier) the incoming caller's caller ID info will pass through the switch to my cell phone. So if David calls Joe at ABC company and Joe's phone has a license seat for mobile twinning and the feature is activated, Joe's cell phone will show David's caller ID, not ABC company's. Has anyone used this feature? I am looking at an IP500 for this reason and this reason only. Any feedback greatly appreciated. Thanks.